|
|
Ghazi Moradi, F. et al, & Huyuk, T. (2014). Character of particle-hole excitations in Ru-94 deduced from gamma-ray angular correlation and linear polarization measurements. Phys. Rev. C, 89(1), 014301–9pp.
Abstract: Linear polarization and angular correlations of gamma-rays depopulating excited states in the neutron-deficient nucleus Ru-94(44)50 have been measured, enabling firm spin-parity assignments for several excited states in this nucleus. The deduced multipolarities of strong transitions in the yrast structure were found to be mostly of stretched M1, E1, and E2 types and, in most cases, in agreement with previous tentative assignments. The deduced multipolarity of the 1869 keV and the connecting 257 and 1641 keV transitions indicates that the state at 6358 keV excitation energy has spin parity 12(1)(-) rather than 12(3)(+) as proposed in previous works. The presence of a 12(1)(-) state is interpreted within the framework of large-scale shell-model calculations as a pure proton-hole state dominated by the pi(p(1/2)(-1)circle times g(9/2)(-5)) and pi(p(3/2)(-1) g(9/2)(-5)) configurations. A new positive-parity state is observed at 6103 keV and is tentatively assigned as 12(2)(+). The 14(1)(-) state proposed earlier is reassigned as 13(4)(-) and is interpreted as being dominated by neutron particle-hole core excitations. The strengths of several E1 transitions have been measured and are found to provide a signature of core-excited configurations.
|
|
|
|
Koolen, B. B., Vidal-Sicart, S., Benlloch, J. M., & Olmos, R. A. V. (2014). Evaluating heterogeneity of primary tumor 18 F-FDG uptake in breast cancer with a dedicated breast PET ( MAMMI): a feasibility study based on correlation with PET/CT. Nucl. Med. Commun., 35(5), 446–452.
Abstract: PurposeThe aim of the study was to evaluate the heterogeneity of primary tumor F-18-fluorodeoxyglucose (F-18-FDG) uptake in breast cancer patients using a dedicated breast PET.Patients and methodsA positron emission tomography/computed tomography (PET/CT) of the thorax was performed 60 min after administration of 180-240 MBq of F-18-FDG in patients with breast cancer. Subsequently, 110 min after injection, a scan was taken with a dedicated high-resolution breast PET [MAMmography with Molecular Imaging (MAMMI)]. Both procedures were performed with the patients in the prone position. Four-point scores were used to compare the intensity (0: none; 1: mild; 2: moderate; 3: high) and heterogeneity (0: none; 1: mild; 2: moderate; 3: high) of F-18-FDG uptake between PET/CT and MAMMI images.ResultsThirty-five patients in whom the primary tumor was visualized on both scans were included in this analysis. The mean primary tumor size was 35.1 mm (range 10-108 mm). The mean intensity score was similar on both devices (2.4 for PET/CT and 2.3 for MAMMI; P=0.439), but the mean heterogeneity score on MAMMI images was significantly higher (PET/CT 1.9 vs. MAMMI 2.3; P=0.005). MAMMI showed a higher heterogeneity score in 11 (31%) of 35 patients, especially in tumors with moderate or high intensity. Significantly higher heterogeneity scores on both PET/CT and MAMMI were seen in large tumors (P=0.005 and 0.014, respectively) and in tumors with high intensity scores (P=0.012 and P<0.001, respectively).ConclusionHeterogeneous tumor F-18-FDG uptake in breast cancer is frequently observed, particularly in large tumors with intense F-18-FDG uptake. It is more often seen on MAMMI PET than on conventional PET/CT. Although the observed heterogeneity should be proven histopathologically, this finding offers a rationale for F-18-FDG-guided biopsies.
|
|
|
|
Ros, A., Lerche, C. W., Sebastia, A., Sanchez, F., & Benlloch, J. M. (2014). Retroreflector arrays for better light collection efficiency of gamma-ray imaging detectors with continuous scintillation crystals without DOI misestimation. J. Instrum., 9, P04009–14pp.
Abstract: A method to improve light collection efficiency of gamma-ray imaging detectors by using retroreflector arrays has been tested, simulations of the behaviour of the scintillation light illuminating the retroreflector surface have been made. Measurements including retroreflector arrays in the setup have also been taken. For the measurements, positron emission tomography (PET) detectors with continuous scintillation crystals have been used. Each detector module consists of a continuous LSO-scintillator of dimensions 49x49x10 mm(3) and a H8500 position-sensitive photo-multiplier (PSPMT) from Hamamatsu. By using a continuous scintillation crystal, the scintillation light distribution has not been destroyed and the energy, the centroids along the x- and y-direction and the depth of interaction (DOI) can be estimated. Simulations have also been run taking into account the use of continuous scintillation crystals. Due to the geometry of the continuous scintillation crystals in comparison with pixelated crystals, a good light collection efficiency is necessary to correctly reconstruct the impact point of the gamma-ray. The aim of this study is to investigate whether micro-machine retro-reflectors improve light yield without misestimation of the impact point. The results shows an improvement on the energy and centroid resolutions without worsening the depth of interaction resolution. Therefore it can be concluded that using retroreflector arrays at the entrance side of the scintillation crystal improves light collection efficiency without worsening the impact point estimation.
|
|
|
|
Diez, S. et al, Bernabeu Verdu, J., Civera, J. V., Garcia, C., Garcia-Argos, C., Lacasta, C., et al. (2014). A double-sided, shield-less stave prototype for the ATLAS Upgrade strip tracker for the High Luminosity LHC. J. Instrum., 9, P03012–16pp.
Abstract: A detailed description of the integration structures for the barrel region of the silicon strips tracker of the ATLAS Phase-II upgrade for the upgrade of the Large Hadron Collider, the so-called High Luminosity LHC (HL-LHC), is presented. This paper focuses on one of the latest demonstrator prototypes recently assembled, with numerous unique features. It consists of a shortened, shield-less, and double sided stave, with two candidate power distributions implemented. Thermal and electrical performances of the prototype are presented, as well as a description of the assembly procedures and tools.
|
|
|
|
Carrio, F., Kim, H. Y., Moreno, P., Reed, R., Sandrock, C., Schettino, V., et al. (2014). Design of an FPGA-based embedded system for the ATLAS Tile Calorimeter front-end electronics test-bench. J. Instrum., 9, C03023–12pp.
Abstract: The portable test-bench for the certification of the ATLAS tile hadronic calorimeter front-end electronics has been redesigned for the present Long Shutdown (LS1) of LHC, improving its portability and expanding its functionalities. This paper presents a new test-bench based on a Xilinx Virtex-5 FPGA that implements an embedded system using a PowerPC 440 microprocessor hard core and custom IP cores. A light Linux version runs on the PowerPC microprocessor and handles the IP cores which implement the different functionalities needed to perform the desired tests such as TTCvi emulation, G-Link decoding, ADC control and data reception.
|
|
|
|
Esperante-Pereira, D. (2014). DEPFET active pixel sensors for the vertex detector of the Belle-II experiment. J. Instrum., 9, C03004–11pp.
Abstract: Active pixels sensors based on the DEPFET technology will be used for the innermost vertex detector of the future Belle-II experiment. The increased luminosity of the e(+) e(-) SuperKEKB collider entails challenging detector requirements, namely: low material budget, low power consumption, high precision and efficiency, and a large readout rate. The DEPFET active pixel technology has shown to be a suitable solution for this purpose. A review of the different aspects of the detector design (sensors, readout ASICS and supplementary infrastructure) and the results of the latest thinned sensor prototypes (50 μm) are described.
|
|
|
|
Gonzalez-Sevilla, S. et al, Bernabeu Verdu, J., Civera, J. V., Garcia, C., Lacasta, C., Marco, R., et al. (2014). A double-sided silicon micro-strip Super-Module for the ATLAS Inner Detector upgrade in the High-Luminosity LHC. J. Instrum., 9, P02003–37pp.
Abstract: The ATLAS experiment is a general purpose detector aiming to fully exploit the discovery potential of the Large Hadron Collider (LHC) at CERN. It is foreseen that after several years of successful data-taking, the LHC physics programme will be extended in the so-called High-Luminosity LHC, where the instantaneous luminosity will be increased up to 5 x 10(34) cm(-2) s(-1). For ATLAS, an upgrade scenario will imply the complete replacement of its internal tracker, as the existing detector will not provide the required performance due to the cumulated radiation damage and the increase in the detector occupancy. The current baseline layout for the new ATLAS tracker is an all-silicon-based detector, with pixel sensors in the inner layers and silicon micro-strip detectors at intermediate and outer radii. The super-module is an integration concept proposed for the strip region of the future ATLAS tracker, where double-sided stereo silicon micro-strip modules are assembled into a low-mass local support structure. An electrical super-module prototype for eight double-sided strip modules has been constructed. The aim is to exercise the multi-module readout chain and to investigate the noise performance of such a system. In this paper, the main components of the current super-module prototype are described and its electrical performance is presented in detail.
|
|
|
|
Pujades, M. C., Granero, D., Vijande, J., Ballester, F., Perez-Calatayud, J., Papagiannis, P., et al. (2014). Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities. J. Radiol. Prot., 34(4), 741–753.
Abstract: In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for Ir-192 and Co-60 HDR applications to account for several different bunker layouts. For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emitted by Ir-192 and Co-60 will reduce the lead thickness by a factor of five for Ir-192 and ten for Co-60. This will significantly lighten the door and hence simplify construction and operating requirements for all bunkers. The adaptation proposed in this study to estimate the air-kerma rate at the door depends on the complexity of the maze: it provides good results for bunkers with a maze (i.e. similar to those used for linacs for which the NCRP 151 methodology was developed) but fails for less conventional designs. For those facilities, a specific Monte Carlo study is in order for reasons of safety and cost-effectiveness.
|
|
|
|
Tarifeño-Saldivia, A., & Soto, L. (2014). Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source. Plasma Phys. Control. Fusion, 56(12), 125013–5pp.
Abstract: This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode.
|
|
|
|
Piersanti, L., Bellini, F., Bini, F., Collamati, F., De Lucia, E., Durante, M., et al. (2014). Measurement of charged particle yields from PMMA irradiated by a 220 MeV/u C-12 beam. Phys. Med. Biol., 59(7), 1857–1872.
Abstract: The radiation used in hadrontherapy treatments interacts with the patient body producing secondary particles, either neutral or charged, that can be used for dose and Bragg peak monitoring and to provide a fast feedback on the treatment plans. Recent results obtained from the authors on simplified setups (mono-energetic primary beams interacting with homogeneous tissue like target) have already indicated the correlation that exists between the flux of these secondaries coming from the target (e.g. protons and photons) and the position of the primary beam Bragg peak. In this paper, the measurements of charged particle fluxes produced by the interaction of a 220 MeV/u carbon ion beam at GSI, Darmstadt, with a polymethyl methacrylate target are reported. The emission region of protons (p), deuterons (d) and tritons (t) has been characterized using a drift chamber while the particle time-of-flight, used to compute the kinetic energy spectra, was measured with a LYSO scintillator.The energy released in the LYSO crystal was used for particle identification purposes. The measurements were repeated with the setup at 60 degrees and 90 degrees with respect to the primary beam direction. The accuracy on the fragments emission profile reconstruction and its relationship with the Bragg peak position have been studied. Based on the acquired experimental evidence, a method to monitor the dose profile and the position of the Bragg peak inside the target is proposed.
|
|
